1. Field of the Invention
This invention relates to a method for forming a suture-receiving hole in an eyeless suture needle characterized in that a hole is formed in the base end of a needle made from an oxidation resisting material, and more particularly to a method for forming a suture-receiving hole in an eyeless suture needle characterized in that a hole is formed by pressing a heat resisting perforating tool in the base end, after the base end of the needle material made of an oxidation resisting material was heated to near melting point.
2. Description of the Prior Art
The usual methods for forming a suture-receiving hole in an eyeless suture needle include: (1) a cutting processing method for cutting by a drill, (2) a weld processing method for welding a tubular member, (3) a discharge processing method for processing by discharging between electrodes in a liquid, and (4) special processing methods for causing the sublimation of a material by using an instantaneous high energy laser or electronic beam. However, all of the above methods have various problems as illustrated below. Also, they have a disadvantage in that it is difficult to cheaply form a hole having good character combining threads with high precision at the basic end of suture needle.
(1) The method for cutting a hole by use of a drill is difficult in the case of needle materials of stainless steel, especially when the hole is below 0.3 mm diameter, and cutting a deep hole of about 4-5 times the hole diameter becomes very costly in relation to the price of the needle and the life of the drill and is impractical.
(2) In the method of welding of a tubular member, welding of a tube to a thin solid material is very difficult, especially as the thickness of the tube becomes thin. There is also a possibility of failure the welding during the cutting process for the purpose of removal of weld flash and also the determination of hole-depth is complex and costly.
(3) In the discharge processing method, the processing speed is slow, and provides a hole that becomes a larger tapered shape at the bottom than at the inlet, and in a hole below 0.4 mm diameter the processing liquid does not circulate and the processing is nearly impossible. Naturally, attempts to make the electrode into a tube have been performed, but unless the hole diameter is fully expanded so that the processing liquid passes through a hole in the tube on account of the blind hole, the hole remains without receiving the processing and also this processing is unusuable.
In the processing method (4) using a laser, an electronic beam and the like, wherein the material is heated instantaneously to a high temperature by laser light or an electronic beam, there is a fatal defect in that the shape of the hole is unstable and the accuracy is poor, because of sublimation of the material.